volume 8 Number io 1980 Nucleic Acids Research Yeast tRNA™16 conformation wheeb: a novel probe of the monoclinic and orthorhombic modeb A.R.Srinivasan and W.K.Olson*

A series of conformation wheels is constructed from the recently refined X-ray crystallographic data of monoclinic and orthorhombic yeast tRNAPhe. These circular plots relate the primary chemical structure (i.e., base sequence) directly to the secondary and tertiary structure of the molecule. The circular sequence of backbone torsion angles displays a unique pattern that is useful both in distinguishing the ordered and disordered regions of the molecule and in comparing the three sets of experimental data. Com-posite conformation wheels describe the fluctuations in the "fixed " param-eters ($', $, X) and independent conformation wheels reveal the changes in the "variable " parameters (u1, cu, $, $') of the three different yeast tRNA 1 ^ models. Additional plots of base-stacking parameters help to vis-ualize the intimate interrelationship between chemical sequence and three-dimensional folding of yeast tRNAPne. The composite data illustrate sev-eral conformational schemes that position the bases of adjacent nucleoside